Binary interpolymers of vinyl chloride



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The present invention relates to novel vinyl chloride interpolymers and to methods for preparing same.

Vinyl chloride homopolymers are Widely employed as a surface coating resin, as a wire insulation resin, and for diverse other purposes. A relatively recent development in the art has been the employment of vinyl chloride polymer insulated Wires as underground electrical cables. The insulation on such underground cables iriust be able to Withstand severe physical punishment and for maximum utility requires vinyl chloride polymers having physical properties superior to those of many of the presently commercially available vinyl chloride homopolymers. In particular, this development requires vinyl chloride polymers having a high tensile strength, a high 100% modulus and a high crush-resistance.

It is known that the physical properties of vinyl chloride homopolymers such as tensile strength, 100% modulus and crush-resistance can be improved by preparing the polymer under such conditions that higher molecular weights are obtained. To obtain such higher molecular weights it has heretofore been necessary to lower the polymerization temperature or to reduce the concentration of free radical generating polymerization initiator employed or both. Such modifications of the polymerization process increase the cost of preparing vinyl chloride homopolymers in that they lower the rate of polymerization and concomitantly the productive capacity of the equipment 7 in which the polymer is prepared. V

A method sometimes proposed for increasing the molecular weight of polymers is to incorporate a small quantity of a cross-linking monomer, i.e., a monomer containing two or more non-conjugated terminal ethylenic groups,

'in the monomer charge. This method has been used successfully with some polymer systems, but it is not generally applicable to the preparation of vinyl chloride polymers of high molecular weight. In particular, it is difficult to find cross-linking monomers which will interp'olymerize with vinyl chloride at satisfactory rates. Moreover, where interpolymers can be formed, they tend to be quite heterogeneous in composition and in most cases the interpolymer contains a highly gelled fraction which is insoluble in most solvents for the vinyl chloride interpolymer. Such interpolymers, because of their heterogeneity and insoluble gel fraction, can not be employed in surface coating compositions.

It is an object of this invention to provide vinyl chloride polymers having improved physical properties.

Another object of this invention is to provide a process for preparing vinyl chloride polymers of improved physi-:

cal properties, which process can be carried out in conventional polymerization equipment.

A further object of this invention is to providea vinyl chloride polymerization process which, with no sacrifice in the rate of polymerization, yields vinyl chloride polymers of improved physical properties.

Other objects and advantages of this invention will be apparent from the following detailed description thereof.

It has been discovered that vinyl chloride polymers of improved physical properties, as compared With vinyl chloride homopolymers prepared under otherwise identical conditions", can be obtained by interpolymeri zingminute' but critical quantities of a polyallyl phosphate ester with vinyl chloride. Such improved vinyl chloride interpolymers contain 0.003 030 weight percent of the polyallyl phosphate ester with the balance" of the interpolyiner United States Patent specific viscosity value with the specific viscosit ice 2 being vinyl chloride. The vinyl chloride interpoly rners of improved physical properties are obtained at rates of polymerization which are fully equivalent to those obtained in the homopolymerization of vinyl chloride.

As noted earlier herein, it is known that the physical properties of vinyl chloride polymers such as tensile strength, modulus and crush-resistance are improved as the molecular weight of the vinyl chloridepolymer is increased. This is true not only for vinyl chloride polymers per se, but also for formulated vinyl chloride polymer compositions containing plasticizers, pigments, fillers and other conventional polymer compounding ingredients. Since the precision of molecular weight determinations is much higher than the precision of determinations of tensile strength, 100% modulus and crushresistance, the comparison of polymer properties in the subsequent examples is based primarily upon polymer EXAMPLE I Part A A vinyl chloride homopolymer is prepared in a stirred autoclave employing the suspension polymerization syste set forth below. 7

Specific viscosity= Component: Parts by weight Monomer 100 Water Suspending agent 0.15 Lauroyl peroxide 0.25

Equimolar interpolymer of vinyl acetate and maleic an hydride. V

The polymerization is carried out at 51 C. and is completed in about 16 hours. Thevinyl chloride homopolymer has a specific viscosity of 0.51.

An interpolymer consisting of 99.97 weight percent of vinyl chloride and 0.03 weight percent of triallylpliosphate is prepared by the procedure f Part A,ab ove' has a specific viscosity of about 0.60. In comparing this the vinyl chloride homopolymer prepared in PartA A it will be noted that, although the interpolynieri U ains only 0.03 Weight percent of triallyl phosphate, the specifi-c viscosity of the resulting interpolyriier is about 18 higher than the value obtained with the vinyl chloride homopolymer'. e e Part" C The vinyl chloride-triallyl phosphate interpolynier of .Part B is compounded into the wire coating formulation set forth below. i I

1 Hydrocarbon type.

spy/3550 The resulting formulation has a tensile strength of about 2600 p.s.i. and 100% modulus of about 1800 p.s.i. By wayof contrast, when the vinyl chloride homopoly- -mer of Example I, Part A, is substituted for the vinyl chloride-triallyl phosphate interpolymer, the resulting formulation has tensile strength and 100% modulus values approximately 100 points lower.

EXAMPLES II--VI Five vinyl chloride-triallyl phosphate interpolymers containing varying quantities of triallyl phosphate are prepared under identical polymerization conditions following the procedure of Example I, Part B. The composition of the interpolymers and the specific viscosities thereof are set forth in Table I.

As seen from the above table, each of the interpolymers containing triallyl phosphate has a higher specific viscosity than the control vinyl chloride homopolymer. Each of the triallyl phosphate containing interpolymers also has a higher tensile strength and 100% modulus than the control vinyl chloride homopolymer. In addition, each of the interpolymers is free of gels and is completely soluble in such solvents as cyclohexanone and nitrobenzene. Accordingly, the interpolymers are well suited for use in paints and other surface coating compositions.

The interpolymers of this invention are binary interpolymers consisting of vinyl chloride and a polyallyl phosphate ester, which for the sake of brevity will sometimes be referred to simply as the allyl phosphate. The allyl phosphates which can be employed in the practiceof this invention conform to the formula:

where R and R are independently selected from the group consisting of a hydrogen atom and a methyl radical and R" is selected from the group consisting of a hydrogen atom, an allyl radical, a methallyl radical, an

alkyl radical, an aralkyl radical, an aryl radical and an alkaryl radical. Typical examples of suitable allyl phosphates include, among others, diallyl monohydrogen phosphate, dimethallyl monohydrogen phosphate, diallyl monomethyl phosphate, diallyl monophenyl phosphate, diallyl mono(4-ethylphenyl)phosphate, diallyl monobenzyl phosphate, etc. The allyl phosphates can be prepared by classical methods that are known in the art and certain of these compounds are commercially available.

The proportions of vinyl chloride and allyl phosphate included in the interpolymers will depend upon the num- 'ber of allyl (or methallyl) groups included in the allyl The interpolymers of the invention are preferably prepared by the well-known suspension polymerization process in which the monomers are dispersed as small droplets in water and polymerized therein. Although a watersoluble interpolymer of vinyl acetate and maleic anhydride has been employed as the suspending agent in the examples herein presented, other known suspending agents such as gelatine, protective colloids, etc. may be employed if desired. The polymerizations are carried out at temperatures in the range of 3070 C. in the presence of free radical generating polymerization initiators such as lauroyl peroxide, benzoyl peroxide, etc.

The interpolymers of this invention have higher molecular Weights and better physical properties than corresponding vinyl chloride homopolymers prepared under identical polymerization conditions. Thus, the process of this invention makes possible the attainment of a superior product at no increase in cost. Alternatively, interpolymers of this invention having equivalent physical properties 'to vinyl chloride homopolymers can be prepared at higher polymerization temperatures. Polymerizing the interpolymers at higher temperatures increases the rate of polymerization and raises the productive capacity of the polymerization vessel in which the reaction is carried out. Thus, the interpolymers of this invention make possible the attainment of a higher productive capacity per unit of capital investment. In general, the productive capacity of a polymerization vessel for the interpolymers of this invention is approximately 30% higher than the productive capacity of the same vessel for a vinyl chloride homopolymer, both of said polymers being polymerized under conditions which give identical molecular weights.

The interpolymers of this invention may be used interchangeably with vinyl chloride homopolymers in virtually all industrial applications. The interpolymers are particularly suitable for use in the insulation of electric wire and particularly for electric wire that is to be employed as underground cable.

The above descriptions and particularly the examples are set forth by way of illustration only. Many other variations and modifications thereof will be obvious to those skilled in the art and can be made without departing from the spirit and scope of the invention. herein disclosed.

What is claimed is:

l. A resinous interpolymer of a binary mixture of monomers consisting of vinyl chloride and an allyl phosphate monomer of the formula:

v where R and R are independently selected from the group consisting of a hydrogen atom and a methyl radical and R" is selected from the group consisting of a hydrogen atom, allyl radical, the methallyl radical, an alkyl radical, an aralkyl radical, an aryl radical and an alkaryl radical; said monomer mixture consisting of 99.95-99.997 weight percent of vinyl chloride and, correspondingly, 005-0003 weight percent of the allyl phosphate monomer when R" in the above formula is selected from the group consisting of an allyl radical and the methallyl radical; said monomer mixture consisting of 99.70-99.99 weight percent of vinyl chloride and, correspondingly, 0.30-0.01 weight percent of the allyl phosphate monomer when R" in the above formula is a substituent other than a member of the group consisting of allyl radical and the methallyl radical.

2. A resinous interpolymer of a binary mixture of monomers consisting of vinyl chloride and an allyl phosphate monomer of the formula:

where R and R are independently selected from the group consisting of a hydrogen atom and a methyl radical and R" is selected from the group consisting of a hydrogen atom, allyl radical, the methallyl radical, an alkyl radical, an aralkyl radical, an aryl radical and an alkaryl radical; said monomer mixture consisting of 99.96-99.995 weight percent of vinyl chloride and, correspondingly, 0.04-0.005 weight percent of the allyl phosphate monomer when R in the above formula is selected from the group consisting of allyl radical and the methallyl radical; said monomer mixture consisting of 99.85-99.98 weight percent of vinyl chloride and, correspondingly, 0.15-0.02 weight percent of the allyl phosphate monomer when R in the above formula is a substituent other than a member of the group consisting of allyl radical and the methallyl radical.

3. A resinous interpolymer of monomers consisting of 99.96-99.995 weight percent of vinyl chloride and, correspondingly, 0.04-0.005 Weight percent triallyl phosphate.

4. An insulated electric wire comprising an electrical conductor carrying an insulating coating of a resinous interpolymer of a binary mixture of monomers consisting of vinyl chloride and an allyl phosphate monomer of the formula:

where R and R are independently selected from the group consisting of a hydrogen atom and a methyl radical and R" is selected from the group consisting of a hydrogen atom, allyl radical, the methallyl radical, an alkyl radical, an aralkyl radical, an aryl radical and an alkaryl radical; said monomer mixture consisting of 99.95-99.997 weight percent of vinyl chloride and, correspondingly, 0.05-0.003 Weight percent of the allyl phosphate monomer-when R" in the above formula is selected from the group consisting of allyl radical and the methallyl radical; said monomer mixture consisting of 99.70-99.99 weight percent of vinyl chloride and, correspondingly, 030-001 weight percent of the allyl phosphate monomer when R" in the above formula is a substituent other than a member of the group consisting of an allyl radical and the methallyl radical.

5. A suspension polymerization process for preparing a resinous interpolymer of a monomer mixture consisting solely of vinyl chloride and an allyl phosphate, which process comprises dispersing the monomers as droplets in an aqueous medium containing therein a suspending agent and polymerizing the monomers at a temperature of 3070 C. in the presence of a free radical generating polymerization initiator; said allyl phosphate conforming to the formula:

where R and R are independently selected from the group consisting of a hydrogen atom and a methyl radical and R" is selected from the group consisting of a hydrogen atom, allyl radical, the methallyl radical, an alkyl radical, an aralkyl radical, an aryl radical and an alk-aryl radical; said monomer mixture consisting of 99.96-99.995 weight percent of vinyl chloride and, correspondingly, 0.04-0.005 weight percent of the allyl phosphate monomer when R in the above formula is selected from the group consisting of allyl radical and the methallyl radical; said monomer mixture consisting of 99.85-99.98 weight percent of vinyl chloride and, correspondingly, 0.15-0.02 weight percent of the allyl phosphate monomer when R in the above formula is a substituent other than a member of the group consisting of an allyl radical and the methallyl radical.

6. A suspension polymerization process for preparing a resinous interpolymer of a monomer mixture consisting solely of vinyl chloride and an allyl phosphate, which process comprises dispersing the monomers as droplets in an aqueous medium containing therein a suspending agent and polymerizing the monomers at a temperature of 30-70" C. in the presence of a free radical generating polymerization initiator; said allyl phosphate conforming to the formula:

where R and R are independently selected from the group consisting of a hydrogen atom and a methyl radical and R" is selected from the group consisting of a hydrogen atom, allyl radical, the methallyl radical, an alkyl radical, an aralkyl radical, an aryl radical and an alkaryl radical; said monomer mixture consisting of 99.95-99.997 weight percent of vinyl chloride and, correspondingly, 0.05-0.003 weight percent of the allyl phosphate monomer when R in the above formula is se lected from the group consisting of allyl radical and the methallyl radical; said monomer mixture consisting of 99.70-99.99 weight percent of vinyl chloride and, correspondingly, 0.30-0.01 weight percent of the allyl phosphate monomer when R in the above formula is a substituent other than a member of the group consisting of allyl radical and the methallyl radical.

References Cited in the file of this patent UNITED STATES PATENTS 2,186,360 Britton et al. Jan. 9, 1940 2,202,846 Garvey et al. June 4, 1940 2,636,027 Coover et al. Apr. 21, 1953 

1. A RESINOUS INTERPOLYMER OF A BINARY MIXTURE OF MONOMERS CONSISTING OF VINYL CHLORIDE AND AN ALLYL PHOSPHATE MONOMER OF THE FORMULA: 